Act One: The reluctant leader
In Mr Duncan Smith's defence, he did not seek the leadership of his unruly party; it was thrust upon him. In 2001, the party was facing a titanic contest between two big beasts, Michael Portillo and Ken Clarke, who were both serious about wanting to be Prime Minister but were both, in contrasting ways, highly controversial.
Each had the support of about one-third of the Conservative parliamentary party, and each had too many enemies, opening up a gap for a compromise candidate who presented less of a threat. Having been persuaded to enter the fray, Mr Duncan Smith emerged as the strongest of the also-rans and then, to widespread astonishment, narrowly overtook Portillo to enter the final round against Clarke.
In that final round, the ordinary party members, with an average age of 67, were given their first chance to participate in a leadership ballot. They voted overwhelmingly for the candidate who was ideologically closer to the one living Tory they truly revered: Margaret Thatcher.
Previously Mr Duncan Smith had been the antithesis of politicians such as Tony Blair and Michael Heseltine, for whom the whole point is to hold high office. In his early years as an MP, Mr Duncan Smith appeared to belong to that small band of principled, ideologically driven parliamentarians who put their beliefs before the pursuit of office and cannot be bought off with threats or bribery.
He was a patriotic military man whose only ambition, apparently, was to preserve the British nation state from being subsumed by Europe. He voted against his own government every timethe Maastricht Treaty was before Parliament, and supported John Redwood's attempt to oust John Major from Downing Street in 1995. Yet, while the air was thick with right-wing plots against the Prime Minister, Mr Duncan Smith did not plot. He walked alone.
Act Two: The invisible leader
Mr Duncan Smith himself said that a new party leader has to establish himself in the first three months if he is to have a real hope of succeeding. It was sheer misfortune that his election victory was announced in the same week as the 11 September terrorist attacks, which drove him off the front pages.
It also prevented him from finding a distinctive voice as Tony Blair took the UK into war, first in Afghanistan and then in Iraq. One of the political assets Mr Duncan Smith brought to his new job was that he was well regarded by the new Republican administration in Washington. He had no intention of sacrificing that by appearing less pro-American than the Prime Minister.
Also, as the months went by, the very qualities that had earned him respect as a back-bench rebel started to work against him. A potential Prime Minister is expected to exude self-belief, but Mr Duncan Smith is diffident. His job required him to be approachable, when by nature he is a loner. As a leader, he has to demand discipline and loyalty from others, when he himself singularly lacked these qualities in John Major's time.
Act Three: The angry leader
Having found that his "never under-estimate the determination of a quiet man" line did not work, Mr Duncan Smith decided last week to stop being the kindly, decent man that he used to be and play at being angry instead. In this new role, he stepped over boundaries that a genuinely nasty man might have feared to tread.
Many outsiders will have been taken aback to hear the Conservative leader use Thursday's big speech to call the Prime Minister a liar and to insinuate that the Liberal Democrat leader, Charles Kennedy, drinks too much. What shocked many Tory delegates, however, was the way he turned on members of his own party.
It is traditional for the leader to do the rounds of regional receptions at the party conferences, which are meant to be good-natured and largely apolitical affairs. But this year Mr Duncan Smith used them to rehearse his new Mr Angry role.
One witness said: "He came in with a dozen heavies who held people back. When Mrs Thatcher came, she only ever had one bodyguard. The atmosphere was very unpleasant. He spoke very, very aggressively. He was swearing - using words like 'damn' and 'my God' which jarred on people - and jabbing his finger.
"When he went out, waiting for him outside was another team to escort him to his next function, and they were all wearing black T-shirts. I was staggered."
Act Four: The beleaguered leader
This weekend, Tory MPs are taking soundings from each other, from party members and from the public, to see whether the week in Blackpool has been as disastrous as they fear. Some have already made up their minds to write to Sir Michael Spicer, chairman of the 1922 Committee, which represents back-bench opinion, calling for a vote of no confidence in the leader.
If 25 or more Tory MPs do so, Sir Michael will call on Mr Duncan Smith to deliver the bad news that he will have to go before a meeting of the whole parliamentary party to fight for his job. He will refuse to divulge the names of any of the 25, but will show the letters, in confidence, to a judge in chambers if anyone doubts his word.
Judging by the tough talk of the past week, Mr Duncan Smith will refuse to admit that the game is up until a vote has taken place, although no one seems to have the slightest doubt that he will lose and have to face the humiliation of being publicly sacked.
After that, there will be a long and possibly nasty leadership contest, with Michael Howard and David Davis among the probable contenders. Michael Portillo's old supporters are hopeful that he will be persuaded to have another try. Even Ken Clarke might run again.
None of this may ever happen, because for most Tory MPs the thought of a leadership contest is even worse than muddling on under Mr Duncan Smith.
One said: "I would do it if I thought we could endure a leadership election, but I don't. I don't want to be spending my Christmas with a leadership election still going on because the Board [of the party] thinks the membership needs time to be consulted, and I don't want a media circus with all the ghosts and monsters of the past coming to haunt us."
Another forecast: "The most likely scenario is to say 'all right, we're going to lose the next election, so let's shut up and get on with it, and when it's over we can get rid of Duncan Smith and start again'. For someone like me, that's the most attractive option. I really have no stomach for another contest."Reuse content